Vain, a. [Compar. Vainer; superl. Vainest.]
Etymology: [F. vain, L. vanus empty, void, vain. Cf. Vanish, Vanity, Vaunt to boast.]
1. Having no real substance, value, or importance; empty; void; worthless; unsatisfying. "Thy vain excuse." Shak. Every man walketh in a vain show. Ps. xxxix. 6. Let no man deceive you with vain words. Eph. v. 6. Vain pomp, and glory of this world, I hate ye! Shak. Vain visdom all, and false philosophy. Milton.
2. Destitute of forge or efficacy; effecting no purpose; fruitless; ineffectual; as, vain toil; a vain attempt. Bring no more vain oblations. Isa. i. 13. Vain is the force of man To crush the pillars which the pile sustain. Dryden.
3. Proud of petty things, or of trifling attainments; having a high opinion of one's own accomplishments with slight reason; conceited; puffed up; inflated. But wilt thou know, O vain man, that faith apart from works is barren James ii. 20 (Rev. Ver.). The minstrels played on every side, Vain of their art. Dryden.
4. Showy; ostentatious. Load some vain church with old theatric state. Pope.
1 more senses
Syn. -- Empty; worthless; fruitless; ineffectual; idle; unreal; shadowy; showy; ostentatious; light; inconstant; deceitful; delusive; unimportant; trifling.
1 other Webster entry under this spelling
Vain, n.
Vanity; emptiness; -- now used only in the phrase in vain. For vain. See In vain. [Obs.] Shak. -- In vain, to no purpose; without effect; ineffectually. " In vain doth valor bleed." Milton. " In vain they do worship me." Matt. xv. 9. -- To take the name of God in vain, to use the name of God with levity or profaneness.
Shades of meaning
Vain (L. vanus, empty) keeps the etymological idea through all changes of meaning; a vain endeavor is empty of result, or of adequate power to produce a result, a vain pretension is empty or destitute of support, a vain person has a conceit that is empty or destitute of adequate cause or reason. That which is bootless, fruitless, or profitless fails to accomplish any valuable result; that which is abortive, ineffectual, or unavailing fails to accomplish a result that it was, or was supposed to be, adapted to accomplish. That which is useless, futile, or vain is inherently incapable of accomplishing a specified result. Useless, in the widest sense, signifies not of use for any valuable purpose, and is thus closely similar to valueless and worthless. Fruitless is more final than ineffectual, as applying to the sum or harvest of endeavor. That which is useless lacks actual fitness for a purpose; that which is vain lacks imaginable fitness. Compare vacant; ostentation; pride.